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Start
[1]
Initial setting
TE = 1 (transmission enabled)
[2]
Read TDRE in SSSR
TDRE = 1?
Yes
Write transmit data to SSTDR
TDRE automatically cleared
Data transferred from SSTDR to SSTRSR
Set TDRE to 1 to start transmission
[3]
Consecutive data transmission?
No
Read TEND in SSSR
TEND = 1?
Yes
Clear TEND to 0
Confirm that TEND is cleared to 0
One bit time
[4]
quantum elapsed?
Yes
Clear TE in SSER to 0
End transmission
Figure 17.6 Flowchart Example of Data Transmission (SSU Mode)
Section 17 Synchronous Serial Communication Unit (SSU)
[1] Initial setting:
Specify the transmit data format.
[2] Check that the SSU state and write transmit data:
Write transmit data to SSTDR after reading and confirming
that the TDRE bit is 1. The TDRE bit is automatically cleared
to 0 and transmission is started by writing data to SSTDR.
[3] Procedure for consecutive data transmission:
No
To continue data transmission, confirm that the TDRE bit is 1
meaning that SSTDR is ready to be written to. After that, data
can be written to SSTDR. The TDRE bit is automatically
cleared to 0 by writing data to SSTDR.
[4] Procedure for data transmission end:
To end data transmission, confirm that the TEND bit is cleared
to 0. After completion of transmitting the last bit, clear the TE
bit to 0.
Yes
No
No
Note: Hatching boxes represent SSU internal operations.
Rev. 1.00 Mar. 12, 2008 Page 571 of 1178
REJ09B0403-0100
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